The Pentagon will declare Thursday that it is lifting a ban on women serving in combat — a decision essentially rendered a fait accompli by more than a decade of war in Afghanistan and Iraq, where many women served ably under fire. Outgoing Defense Secretary Leon Panetta is expected to make the announcement, based on a recommendation from Army General Martin Dempsey, Chairman of the Joint Chiefs of Staff.

The historic change will open up hundreds of thousands of jobs in infantry, armor and other previously all-male units from which women have been formally barred under a 1994 Pentagon rule. Ultimately, they could even be allowed to serve in special-operations units, including the Army’s Delta Force and the Navy’s SEALs.

Women who missed the opportunity to serve in combat cheered the change. “All jobs should be based on qualifications, not gender,” says Battleland contributor Darlene Iskra, the first woman ever to command a Navy ship.

But the decision goes deeper than the post-9/11 wars. With an all-volunteer military, the Pentagon needs women in its ranks. Beyond that, the fluid nature of the 21st century battlefield has rendered long-ago battle maps, with a clear demarcation between front lines and rear echelons, as dated as muskets and bayonets. Basically, it has become untenable for the U.S. military to pretend its female troops are not engaged in combat.

Many women have griped that the wars in Afghanistan and Iraq essentially placed them on the front lines, without getting the combat credentials often needed for promotions. Women constitute about 14% of the U.S. military’s 1.4 million active-duty personnel. While women have totaled more than 10% of those sent to war zones, they have accounted for 1.82% of those wounded and 2.26% of those who died.

Those numbers will climb as women move deeper into the combat arms. “We’ve had over 250,000 deployed and 144 given their ultimate sacrifice,” Army General Ann Dunwoody said of the post-9/11 wars, shortly before her retirement last year. “I think some of our policies are lagging and are catching up with the current employment of women,” the U.S. military’s first female four-star general added. The change is also likely to raise questions about continuing to require only males, once they turn 18, to register with the Selective Service so they can be summoned to fight, if needed, via a draft.

There is no law barring women from combat, and it remains to be seen if some in Congress try to fight to change. But the initial reaction was largely positive. Senator Patty Murray, a Washington Democrat, called it a “historic step for recognizing the role women have, and will continue to play, in the defense of our nation.” The head of the Senate Veterans’ Affairs Committee added that since 9/11, “thousands of women already spent their days in combat situations serving side-by-side with their fellow male service members.”

With Panetta’s green light comes the tough part: ensuring there are sufficient women in uniform who want combat jobs and that they are physically capable of performing them. In the past, career-minded female officers have been more interested in that option than enlisted women.

If, as it appears will be the case, women will have to meet the same physical standards as men, that too could whittle away at the number of women eligible for combat slots. A female Marine officer caused a stir last summer when she asserted that “we are not all created equal, and attempting to place females in the infantry will not improve the Marine Corps as the nation’s force-in-readiness or improve our national security.” The only two female Marines in the corps’ infantry-officer training course the first time it was open to them last year dropped out.

A husband-and-wife Marine couple countered that the combat-exclusion policy “institutionalizes the concept that all male Marines, based on gender alone, are capable of performing duties in the combat arms, while all female Marines similarly are not.” Iskra warned that requirements should not be brandished to block otherwise qualified women. “The requirements need to be based on real requirements,” she says. “Too much in the past, height and weight requirements, for example, were used to exclude candidates who would otherwise be able to do the job.”

Battleland contributor Elspeth Ritchie, who has written about women at war, served as the Army’s top psychiatrist before retiring as a colonel in 2010. She suggests the policy change simply acknowledges reality. “We — female soldiers — were in combat,” she said Wednesday. “I came under fire. I carried a weapon. I earned three different combat patches from Somalia and Iraq. It seemed a farce to proclaim that we were not.”

Nearly a year ago, Panetta signaled that he was open to allowing women into more combat slots when he decided to allow them to serve with forward-deployed combat units in support jobs. “Women are contributing in unprecedented ways to the military’s mission,” he said last February. “We will continue to open as many positions as possible to women so that anyone qualified to serve can have the opportunity to do so.”

Despite that pledge, four women recently sued Panetta and the Pentagon, saying the ban was a “brass ceiling” hindering their advancement through the ranks.